If the player uses the tin cup to make noise
you hear the noise of a door flinging open and someone approaching. He begins to yell.
“Which one of you is making that noise?”
A portly guard walks into your view, and he appears to be wearing armor similar to the local town guards uniform.
You see the glint of a keychain hanging from his belt.
If a player coerces him, he will approach the bars allowing the player an opportunity to pickpocket him.